This invention relates to filled and unfilled matrix materials of aromatic polyurethanes having at least a diphasic structure and a process for their production.
Polyurethanes have been used as industrial materials even though it is known that the urethane bond tends to break down at elevated temperatures. Aliphatic polyurethanes however are sufficiently stable for the synthesis of thermoplastically workable materials. Aromatic polyurethanes are less stable under these conditions because the aromatic urethane bond is more thermolabile. Due to this thermolability, such aromatic urethanes (e.g., reaction products of phenol and aromatic polyisocyanates) are used as thermal isocyanate releasing compounds. That is, the phenol as well as the polyisocyanate is released from the aromatic urethane at temperatures of around 140.degree. C.